This invention relates to semiconductor manufacture and processing and, in particular, to a backplane assembly for contacting and regulating the temperature of a semiconductor substrate during processing in a semiconductor processing system.
The fabrication of integrated circuits in and on a semiconductor substrate involves multiple processing steps which are serially performed in a succession of semiconductor processing systems and which have the ultimate objective of creating arrays of interconnected devices. Semiconductor processing systems incorporate one or more substrate processing stations, which are configured to perform processing steps, such as depositing a thin film of a coating material onto an exposed surface of a substrate or plasma cleaning the exposed surface to remove a contamination layer, such as an oxide, from the exposed surface prior to deposition. Although such conventional semiconductor processing systems are generally suitable for processing substrates, these systems have certain significant drawbacks that limit their application for fabricating integrated circuits.
A typical semiconductor processing system requires the integration of numerous sub-assemblies into a single vacuum chamber. The sub-assemblies cooperate to perform one or more processing steps in the sub-atmospheric environment of the vacuum chamber. Among the sub-assemblies are substrate supports which hold and support the substrates during processing. Substrate supports may be constructed of a substrate holder which secures a substrate with a clamping structure and a backplane having a contact surface that engages the substrate secured by the substrate holder. The backplane is used to regulate the temperature of the engaged substrate during processing. For example, the backplane may be provided with a heating element for elevating the temperature of the substrate. Heat is transferred by thermal conduction between the heated backplane and the substrate. To increase the uniformity of the heat transfer, a flow of a heat transfer gas may be provided between the substrate and the contact surface.
Conventional semiconductor processing systems have complicated designs which are difficult and expensive to fabricate and maintain. The disassembly and reassembly of the individual sub-assemblies from the vacuum chamber is tedious and often requires that the entire processing system be shut down for as much as one or more days to repair or replace components. Even a shutdown measured in hours can be costly as the downtime has a ripple effect along the production line, which significantly decreases the throughput of the production line and further increases the indirect costs of maintaining each individual processing system. Production equipment is only useful when actually making a product and any production stoppage is expensive when an entire production line is idled.
Common semiconductor substrates are flexible circular wafers that are available in a number of outside diameters, for example, 100 mm (4 inch), 150 mm (6 inch), 200 mm (8 inch) and 300 mm (12 inch). The contact surface of the backplane has a surface area specified to abut a major portion of the rear face of the substrate opposite the exposed face undergoing processing by the semiconductor processing system. When the substrate processing system is reconfigured to reflect a change in the dimension and/or configuration of the substrates to be processed, the existing backplane must be removed from the system and replaced with a different backplane having a contact surface of suitable dimension and configuration to engage the substrates of differing dimension and/or configuration. To perform the replacement, the vacuum chamber of the system is vented to atmospheric pressure and the various cables and fluid lines are disconnected from the existing backplane. The existing backplane is unfastened and removed from its mounting opening. In certain semiconductor processing systems, the entire plenum of the vacuum chamber must be opened to afford maintenance personnel the access required to remove the backplane. During the backplane exchange, atmospheric gases, such as water vapor and other volatile species, can enter through the mounting opening, or open plenum, and adsorb on internal surfaces of the vacuum chamber. The adsorbed amounts of atmospheric and volatile species is commensurate with the duration of the atmospheric exposure. After the different backplane is mounted and the vacuum chamber is resealed and evacuated, the return of the system vacuum to an acceptable sub-atmospheric pressure level depends upon the quantity of adsorbed atmospheric species. In extreme cases, the semiconductor processing system may require a heat treatment or bake to remove the adsorbed species. Thus, the replacement of a conventional backplane involves not only the time required for the actually exchange but also the time required to reestablish an acceptable vacuum pressure in the vacuum chamber.
An objective of this invention is to provide a backplane that is readily adaptable to a change in the dimension and/or configuration of the substrates being processed by the semiconductor processing system.
The forgoing objective has been accomplished, according to the present invention, by providing a backplane assembly for a substrate processing system comprising a backplane base mountable within the vacuum chamber of a substrate processing system and at a position suitable for processing substrates, a first faceplate removably mountable to the backplane base, and a second faceplate removably mountable to the backplane base. The first and second faceplates are each sized to be insertable through an access port of the vacuum chamber for mounting to the backplane base. The first faceplate has a first contact surface dimensioned and configured to provide an efficient thermal contact with a correspondingly dimensioned and/or configured first type of substrate. The second faceplate has a second contact surface dimensioned and configured differently than the first contact surface to provide an efficient thermal contact with a correspondingly dimensioned and/or configured second type of substrate. The first and second faceplates are alternatively mountable to the backplane base to form a mated configuration therewith for alternatively processing the first and second types of substrates, respectively, in the vacuum chamber. The backplane assembly may be reconfigured by exchanging the first and second faceplates so that the substrate processing system can process the two different types of substrates. Additional faceplates may be provided to permit the substrate processing system to process more than two types of substrates, wherein each type of substrate has a differing dimension and/or configuration.
Embodiments of the backplane assembly of the present invention may be provided in the form of a retrofit kit that includes a backplane base and at least two interchangeable faceplates configured to collectively replace the conventional one-piece backplane used in certain substrate processing systems. Each of the faceplates in the retrofit kit is dimensioned and configured to be compatible with a correspondingly dimensioned and/or configured substrate so that the processing system can be adapted to process differently dimensioned and/or configured substrates.
According to the present invention, a method is provided for processing substrates of different configurations and/or dimensions on a sequential basis in a substrate processing system incorporating a ventable vacuum chamber with an access port. A backplane assembly is provided having a backplane base mounted in the vacuum chamber with a position suitable for processing substrates, a first faceplate removably mounted to the backplane base, and a second faceplate removably mountable to the backplane base when the first faceplate is demounted from the base. The first faceplate has a first contact surface dimensioned and configured to provide an efficient thermal contact with a first type of substrate. The second faceplate has a second contact surface dimensioned and configured to provide an efficient thermal contact with a second type of substrate which is configured and/or dimensioned differently than the first substrate. A first substrate is placed on the first faceplate and processed while the access port is closed and the vacuum chamber is under sub-atmospheric pressure. The access port in the vacuum chamber is opened to provide access to the first faceplate and the first substrate is removed. The first faceplate is removed from the backplane base without removing the backplane base from the vacuum chamber. The first faceplate is removed through the open access port and the second faceplate is inserted into the access port through the open access port. The second faceplate is then mounted to the backplane base without removing the backplane base from the vacuum chamber. A second substrate is placed on the second faceplate and processed while the access port is closed and the vacuum chamber is under sub-atmospheric pressure.
By virtue of the foregoing, there is provided a backplane assembly that increases the operational efficiency of a substrate processing system by reducing the complexity of the system and minimizing the cost and downtime when the system is retooled for processing substrates of a different dimension and/or configuration. The present invention provides backplane assemblies having a backplane base that is mountable to the vacuum chamber and two or more removable faceplates that are mountable to the backplane base without removing the backplane base from the processing chamber. Each of the faceplates has a contact surface dimensioned and configured to accommodate a correspondingly dimensioned and/or configured substrate to comply with a change in the type of substrate being processed by the substrate processing system. The present invention is compatible with, and can be retrofitted to, substrate processing systems of the prior art that lack such a capability for rapid and simple reconfiguration to reflect a change in the dimension and/or configuration of the substrates being processed.
These and other objectives and advantages of the present invention will be more readily apparent from the following detailed description.